Here in the northeast this was a popular method for some communities to add fire alarm telegraph circuits to pole tops. The latter (until the early teens) were typically mounted above everything else because these lines were vital life-or-death communications between the residents and the local fire alarm telegraph station. In other words these circuits had utmost priority and were mounted atop poles so that no other wires could interfere with them. Sometimes short crossarms were used on poletop extentions like this one. When telephone paired-cable and improved electric distribution lines (with utility codes and safer construction standards) gradually entered the scene by the teens, fire alarm circuits were often run beneath the power lines (and above phone lines and/or cables).